If high-frequency elements (HF-elements) are to be switched on temporarily, and if there is no suitable control connection, often the operating voltage is switched. Different variants of this are possible, as shown in FIG. 1. This involves direct switching of the operating voltage. Furthermore, indirect switching by way of a control input (a so-called shut-down) is also possible.
In the case of fast switching-on processes the switching unit comprises, for example, individual transistors that have correspondingly fast switching times. As a rule, relays or integrated switches are too slow for time-critical applications.
If the switching unit is located directly on the operating voltage of the HF-element, switching is either by way of relatively slow PNP transistors, or, where fast NPN transistors are used, an adequate control level must be ensured.
If the switching unit is located on the ground port, then in the case of HF-elements it is located in the so-called hot path, i.e. said switching unit is incorporated in the HF characteristics of the arrangement or of the HF-element.